The adjustment will take effect by the first day of the month following the date of the redetermination notice. For example, if an enrollee reports a change in income on June 25 and the marketplace verifies the change and sends a redetermination notice to the enrollee on July 3, the change will be implemented on August 1. (45 C.F.R. § 155.330).
On Private Health Insurance Coverage & The Health Insurance Marketplace